Device for the longitudinal control of aeroplanes



3, 1933- E. T; D. FLORESTA DEVI CE FOR THE LONGITUDINAL CONTROL OF AEROPLANES Filed March 9, 1932 ERCOLE TRIGONA DELLA FLORESTA INVENTOR ATTORNEYS Patented Oct. 3, 1933 PATENT OFFICE DEVICE FOR THE LONGITUDINAL CONTROL OF AEROPLANES Ercole Trigona Della Floresta, Vigna (ii V8110, (Roma), Italy Application March 9, 1932, Serial No. 597,662, and in Italy March 25, 1931 6 Claims.

It is known that, for a given shape of an aeroplane, once fixed the position of its centre of gravity, there will always be, and in the case of a motor-airplane there may exist a certain trim for which is obtained the equilibrium round the centre of gravity of the longitudinal moments of all the acting forces with the exclusion of the aerodynamical reaction on the tail plane. Consequently, for any specific trim, the aerodynamic reaction of the tail is nil, and the tail plane has no longer a supporting effect but only a stabilizing effect. When the hinge moment due to the weight of the horizontal rudder itself, is duly balanced, the said rudder sets itself and remains spontaneously in the direction of prolongation of the fixed plane, and the pilot, when intending to set any desired variation of trim, has to overcome the reactions of the control rod which always start from zero on both sides of the movements.

In these conditions, the best qualities of responsiveness of the control as well as those for the stability of the aeroplane are obtained, and it is also possible to always utilize the control through its whole amplitude in both directions.

In order that the conditions of control and of stability above mentioned may be realized, not merely in one, but in many conditions of trim, it is necessary to deform the aeroplane, by preferably deforming the wing, so as to secure the balance without the intervention of the aero-dynamical reaction of the tail.

The present invention has reference to a device, which hereinafter will be called trim control to be applied to aeroplanes in addition to the usual steering control. The said trim control, which must be irreversible, is designed to determine the shape that the aeroplane must assume in order to attain the desired trim and to obtain the above mentioned conditions of control and of stability. The steering control involves the usual rod of the horizontal rudder, which is reversible as usual and is always freely accessible to the pilot.

The deformation of the wing can be accomplished in various known ways. It must however comply to the condition that any variation of shape which causes a variation in the lifting power of the aeroplane, must also cause a suitable variation of the longitudinal momentum of the centre of gravity for compensating and annulling the reaction on the tail.

For this purpose the trim control must be such as to establish a connection between the movable parts of the wing and the tail plane, capable of producing a relative movement of these parts which will satisfy that feature of the law, which must be found by test and experience for each particular type of aeroplane, either in the wind tunnel or in actual flight, so as to ensure the above mentioned conditions of control and of stability.

Whenever it is desired to employ the usual con- 50 trol appliances for the deformation of the wing, the trim control will be set in such a way as to establish a. correlative variation between the trim of the tail plane and the zero or inactive position of the said control appliances, it being understood 5 that the zero or inactive position corresponds to the position in which they do not produce any active effect.

In the accompanying drawing, which serves to illustrate schematically by way of example, 7 a form of embodiment of the device according to the present invention, a. trim control device is shown in perspective view, which applies to the case in which the deformation of the wing is obtained by varying in the same direction the 7 angle of the lateral balancing planes, and in which the variable movement of the tail plane is obtained by means of a guiding slot, the outline or profile of which defines the law of the movement. so

As shown in the drawing, the device is supposed to be, fitted on to an aeroplane in which the wing is provided with two lateral balancing wings 1, which, with the trim control, may be lifted or lowered simultaneously, so as to vary the carrying power of the wing, without however preventing or disturbing the independent movements required by the steering control.

In order to obtain this, the control rod 2 oscillating in' the spherical bearing 3, for obtaining the alternate control of the balancing wings, is maintained, and a subsidiary lever 4 is added, which in its oscillating movement causes the rotation of a sleeve 5, the inside of which is provided with two opposite screw threads into which are screwed the correspondingly threaded ends of two rods 6, which consequently are caused to approach or to depart from each other when the said sleeve rotates. These rods are slidably mounted into the guides 7, thus causing the relative movement of the pivots 8 on which the angle levers 9 used for the normal control of the lateral wings, are pivoted. The relative approach or distantiation of the pivots of the levers 9, cause the lateral balancing planes to be more or less lifted or lowered by the same amount, if the control rod 2 is placed in the center, and at the same time they maintain always the possibility of being controlled by means of alternate movement when the rod 2 is moved sideways.

To the subsidiary lever 4 of the trim control, is also applied a tension rod 10 by means of which the movement of the tail plane can be varied, by causing it to rotate round the axle 12 by sliding the guides of a guide slot the contour of which is designed in accordance with a law found by experiment, giving the relation of the movements of the tail plane, and of the guide slot above described, it is to be understood.

that in order to obtain the same results, any other mechanical connecting means can be used, adapted and suitable to ensure the required relations between the deformation of the wing and the movement of the tail plane, with theobiect of obtaining those characteristics of stability and of control for which the device is intended.

In addition it is clear from the aforesaidthat the device applied to the tail and all other arrangemeuts connected with it, can also be applied, with suitable modiflcations, also to aeroplanes in which the stability and the longitudinal control are obtained by means of 'a control plane disposed in front of the wing and which replaces the tail in all its duties.

It may also be pointed out that the lever or any other means which, may be used in, its place for the trim control, can also be used for controlling simultaneously other movements of the aeroplane, for example it may be used for the handle control of the motors so as toobtain, in relation to a certain regime of the aeroplane, a determined fraction of the total power which the motors can develop, on condition however that the usual steering control is left always independent, and completely at the disposal of the pilot. v

I claim:

1; In an aircraft having a stabilizer plane, wings and a horizontal elevator and provided with the usual reversible steering control adapted to producea given deformation of the wings and horizontal elevator,-an irreversible trim control adapted to simultaneously adjust from time to time both the deformation of the wings and the position of the stabilizer plane to the trim of flight desired by the pilot and thereby eliminate all aerodynamic reaction on the horizontal elevator and provide for exclusive steering of the aircraft in theusual way by means of said reversible steering control.

2. Device for the trim control of an aircraft according to claim 1 provided with lateral stabilizing fins connected to the horizontal elevator so that the angle of incidence of said fins and elevator may be simultaneously varied in the same direction by means of the irreversible trim control, and a member on the aircraft having a guide slot of predetermined form effecting the variation of the incidence between the stabilizing fins and the horizontal elevator.

tion in order to vary the carrying capacity and longitudinal momentum of said wing and simultaneously operative to correspondingly vary the position of the horizontal elevator to a position avoiding aerodynamic reaction on the horizontal elevator, whereby to subsequently freely control theaircrait by means of the steering control in attained condition of trim control.

4. An irreversible trim control system for an aeroplane having both lateral balancing planes and a tail plane, as well as a steering control rod controlling the same by means of oscillable pivoted levers connected to said planes and said control rod in known manner for altering the inclination of said planes, a universal pivot for said steering rod adapting said rod to oscillate in all directions, which steering control rodwhen moved laterally will produce alternate movement of said planes, there being a trim control lever, andspacedpivots for said oscillable levers connected to said trimccntrol lever and interconnected by means of a threaded sleeve, so that rotation of the sleeve in one direction will further separate said pivots and rotation in the opposite direction will draw them mutually-toward each other upon operation of said trim control lever and will simultaneously vary the angle of inclination of the balancing planes and vary the angle of movement of the tail plane, independently of theusual control of the alternate movement of the lateral planes by means of the steering control lever.

5. A trim system according to claim 4 for an aeroplane having devices connected to the trim control lever for varying the lifting power of the wing and for setting the tail plane, there being devices for controlling the motors and a handle for operating said motor control devices, and means connecting said trim control lever with said latter handle in order to provide in every attainedv condition of the aeroplane, a corresponding fraction of the total possible output of said motors.

6. An irreversible trim control system according to'claim 1 applied to an aircraft having the wing thereof forwardly provided with the steering devices for the longitudinal stabilization of the aircraft.

ERCOLE TRIGONA DELLA 

